The present invention relates to the field of powering systems and, more particularly, to capacitor-powered powering systems and associated methods for starting engines and providing powering auxiliary electrical devices in a vehicle.
Engines such as those used to power automobiles and commercial vehicles typically are started by turning an ignition key. Turning the key causes a connection between a starter relay coil or solenoid switch and the positive terminal of a vehicle battery thereby energizing the coil and closing a contact on the relay. With the contact closed, the vehicle""s starter motor is connected to the vehicle battery so as to crank the engine. In conventional starters, when the contact closes, it makes contact with a metal disc which completes a connection between the positive terminal of the battery and the primary terminal of an ignition coil. The engine is started in a conventional internal combustion engine by rotating a flywheel until the engine fires and is able to run on its own power, commonly referred to as cranking the engine. The flywheel typically is rotated by the starter motor, which is fed with current from the battery. After the motor starts, the ignition switch contact returns to its normal operating position, and the starter relay switch opens, thereby breaking contact with the disc.
Essentially, an automobile or commercial vehicle powered by a conventional internal combustion engine requires a starter that acts as a separate electric motor to rotate the engine crankshaft so as to start or crank the engine. Thus, to successfully start the engine, the starter must be able to rotate the crankshaft at a speed sufficient to fire-up the engine. The starter is electrically powered by the automobile battery, which also provides power to various vehicle devices such as the exterior and interior lights, the horn, temperature and fuel gauges, and a host of other accessory devices commonly found on the vehicle.
More generally, because the starter requires power to function, the vehicle requires a source of energy stored in a quantity sufficient to crank the engine while also providing power to other devices. In conventional systems, the power is supplied by the battery vehicle as already described. The battery also must power the vehicle""s electrical system. The electrical systems of standard automobiles and commercial heavy-duty vehicles, at least since 1975, ordinarily have included an ever increasing number of various electronic control units (ECUs) of ever more complexity. Today, ECUs perform various critical functions on a vehicle. For example, injection of fuel into the combustion chamber on an internal combustion engine can be controlled by an ECU so that an electromagnetic injector pulses on-off so as to supply fuel quantities in a desired proportion to the air-intake. Similarly, ECUs are ordinarily used to control such electronic devices as door locks and outer mirrors on the vehicle. Of particular relevance in the context of the present invention, ECUs are frequently used to control the operation and sequencing of operations necessary for starting a vehicle.
The amount of power that must be supplied to power the electrical system as well as power the starter used to crank the engine is a function of the conditions under which the vehicle is operated. For example, during cold weather, the engine is more difficult to start thus requiring more energy to crank, and extra loads arise when devices such as the heater are left on while the engine is turned off. Thus, there is an ever prevalent need to provide the vehicle with a power supply that is both reliable and capable of providing power in a quantity sufficient to crank the vehicle engine under various operating conditions.
Power conventionally has been supplied in vehicles by standard lead storage batteries. A long-recognized limitation of lead storage batteries, however, is the batteries"" inherent tendency toward relatively rapid depletion. Specifically, it has been estimated that such batteries possess an expected operation life of approximately one year. With continuous operation, moreover, the internal resistance of such a lead storage battery increases such that the battery""s depletion occurs at an increasing rate over time.
Attempts have been made to provide more reliable sources of power for starting engines and powering electrical devices in vehicles. U.S. Pat. No. 5,146,095 to Tsuchiya et al., titled Low Discharge Capacitor Motor Starter System, for example, suggests supplementing the power supplied by a conventional vehicle battery by combining the battery with a high-density capacitor (also commonly referred to as a double-layer or molecular capacitor). Tsuchiya et al. requires that the capacitor be disconnected from the starter at all times save immediately prior to cranking the engine when the capacitor must be coupled to the starter in order to energize the starter for cranking. A more fundamental limitation of Tsuchiya et al., however, is that the battery nevertheless remains essential because, it is the battery that maintains the charge of the capacitor. Given the ever present need to maintain the charge on the capacitor in order to crank the engine, the useful life of a Tsuchiya et al. system remains substantially constrained by the useful life of the battery, as it is the battery that maintains the capacitor""s charge.
Similarly, U.S. Pat. No. 5,207,194 to Clerici, titled System for Starting An Internal Combustion Engine For Motor Vehicles, suggests using a high-capacitance capacitor to supply power to the starter to crank a vehicle engine. Specifically, Clerici provides a set of switches that in a xe2x80x9csecond conditionxe2x80x9d connect the capacitor to the starter to power the starter when cranking the engine. In the xe2x80x9cfirst condition,xe2x80x9d however, the switches connect the capacitor to the battery so that the capacitor can be charged by the battery. Hence, like Tsuchiya et al., Clerici also requires an adequately charged battery in order to maintain the charge on the capacitor in order to crank the engine. Thus, as with Tsuchiya et al., the usefulness of the Clerici system is constrained by the need for a charged battery in order to sustain the capacitor.
U.S. Pat. No. 5,925,938 to Tamor, titled Electrical System For A Motor Vehicle, also suggests using a capacitor and battery device for cranking an engine and powering a vehicle electrical system. Tamor, though, seeks to overcome the limitations inherent in Tsuchiya et al. and Clerici, by charging the capacitor with the alternator and/or battery. Power delivery in Tamor is current-controlled by a resistor-and-diode device that limits current from the battery to the starter when the engine is being cranked and allows current from the alternator to the capacitor and battery when the engine is running. A limitation noted in Tamor itself, however, is that the capacitor store relatively little energy and that capacitor recharging occur only infrequently. This is necessitated by the need to reduce the electrical loss that occurs through the resistor of the current control whenever it is necessary to recharge the capacitor off the battery.
There is thus the need for a system that provides power rapidly and efficiently to a vehicle starter to crank the vehicle""s engine, powers the electrical system of the vehicle, and yet is also reliably maintained for continuous use over a prolonged period for powering both the starter and the electrical system.
With the foregoing in mind, the present invention advantageously provides an engine ignition and powering system that provides increased power for cranking an internal combustion engine and powering auxiliary electrical devices in a vehicle. An additional advantage of the present invention is the system""s enhanced reliability under all operating conditions. Still further advantage of the present invention is the ability to reliably maintain the system""s capabilities over prolonged periods of use. Another distinct advantage of the present invention is that the system provides cranking power to the engine independently of whether or not power is available from a conventional battery; a conventional battery can be advantageously incorporated as part of the system, but is not essential for starting the engine.
Moreover, a further advantage of the present invention is that the system also can power auxiliary electrical devices in a vehicle regardless of whether or not power is available from a conventional battery. This advantage can be critical even with a vehicle powered by both a capacitor and battery. Virtually all modern vehicles rely on various ECUs, and these ECUs include ones essential for controlling the sequence and operation of devices used to start the vehicle. Thus, in a vehicle disabled by a discharged battery, it is necessary to power not only the motor of the starter but also ECUs associated with engine starting. The system, according to the present invention, provides this critical capability.
Among the other distinct advantages provided by the present invention are control mechanisms that are operably efficient and easy to manufacture, especially as compared to conventional systems currently available. Yet an additional advantage is that the system can easily be incorporated into currently designed vehicles. As described herein, below, the features of the system are particularly advantageous when incorporated in heavy-duty vehicles commonly employed for transportation, construction, and agriculture.
The present invention, more specifically, provides an enhanced-power, capacitor-based starting system. The system incorporates a specialized capacitor having additional cells (i.e., an auxiliary-celled capacitor) that provide enhanced cranking power to the engine. As explained more fully below, it is recognized by the present invention that the powering capability of the capacitor is a function of the number of cells and accordingly the number of cells is dictated by the size of the engine. Thus, according to the present invention, adjustment of number of the capacitor cells provides an efficient method of adapting a capacitor so as to function effectively when incorporated into a vehicle having any set of engine, starter, and alternator parameters.
The system controls energy exchanges among the capacitor, starter, and alternator such that the starter and solenoid coils are supplied with power solely by the capacitor during the starting cycle thereby ensuring that starts are fast and efficient. When the engine has been started and is running under its own power, the system directs power from the alternator to the capacitor so that the charge of the capacitor is reliably maintained under virtually any operating conditions. More specifically, the system automatically connects the capacitor and the alternator in response only to a signal supplied by the alternator in the form of electrical current generated only if the alternator is operatively functioning.
Preferably control is provided using a single switchxe2x80x94more preferably a magnetic switch (solenoid) or an electron field effect transistor (FET)xe2x80x94that isolates the capacitor from the battery and the rest of the electrical system of the vehicle when the alternator is not generating electrical current. The alternator current provides a signal to close the otherwise open switch and connect the alternator and the capacitor. Preferably, when the engine is running and the alternator is producing current, the alternator""s xe2x80x9cIxe2x80x9d terminal signals the switch to close thereby permitting the current generated by the alternator to flow to the capacitor as well as the battery so that both are charged with the vehicle alternator.
At other times when the engine is off and the switch accordingly is open, the capacitor is electrically isolated. This accomplishes two functions. Firstly, the capacitor is protected from being discharged by any electrical item on the vehicle (including, in the case of a large heavy-duty vehicle, electrical items in the cab or tractor). Secondly, the battery can be discharged while the capacitor is electrically isolated so that accessory devices are powered by the battery rather than the capacitor. For example, with respect to a commercial vehicle such as a heavy-duty cab and trailer rig, the driver/operator can power up the interior lights and heater in the cab while the engine is off. The amount of energy taken from the battery can also be controlled by the system.
Power levels are controlled, for example, using a voltage enhancer. Specifically, the amount of power can be adjusted through a converter that steps up the voltage between the alternator and the capacitor to thereby increase the amount of power supplied to the capacitor by the alternator as it simultaneously supplies power to the engine battery without any step-up. Thus, the capacitor is optimally charged using, for example, a dc/dc converter when the engine is running, the dc/dc converter stepping up voltage only to the capacitor, not the rest of the electrical system in the vehicle.
A particular advantage of the present invention, however, is that neither the enhancer nor the battery are essential to the system. Firstly, in recognizing the heretofore unrecognized relation between the power requirements of the starter (a function of the engine size, which also determines the requirements of the alternator) and the power supplied by the capacitor, the system accordingly allows the capacitor capabilities to be adjusted to accommodate the absence of a voltage enhancer regardless of and without requiring any modification of the operational parameters of the engine, starter, or alternator.
Secondly, the battery is not essential because the capacitor is able to supply sufficient power to drive the starter in cranking the engine and is recharged exclusively by the alternator. The ideal function of the battery is to power the ECUs of a vehicle even when the engine is not running. Accordingly, as already described, the system provides a control device that essentially isolates the capacitor from the ECUs when the alternator is not supplying current that can recharge the capacitor. Relatedly, though, it is recognized according to the present invention that because ECUs are essential in starting most modern vehicles, power must be available to the ECU even if the starter is powered by a capacitor. Therefore, the system provides an override that permits a user to selectively engage the capacitor even though the engine is off so as to power the ECUs in the event, for example, that the battery is completely disabled. Thus, the engine in an ECU controlled vehicle therefore can be started even without the battery; if the vehicle is disabled by a discharged battery, the user need only simultaneously engage the override and the starter. The ECU is then powered and the starter cranks the engine, both powered solely by the capacitor.
The present invention further provides a method for providing enhanced power to crank the engine of an automobile or commercial vehicle using capacitor-supplied power. The method further includes electrically isolating the capacitor from the automobile""s or commercial vehicle""s battery at preselected times, preferably by interposing a switch (e.g., a magnetic switch or electron FET) between the capacitor and the battery, the switch being responsive to current generated by the alternator. Another method aspects of the present invention is charging the capacitor using the vehicle alternator when the engine of the vehicle is running, preferably using a step-up converter to increase the voltage between the alternator and the capacitor.
Yet a further method aspect of the present invention includes electrically isolating the capacitor when the engine is not running, preferably by opening a magnetic switch or FET as already described above. This prevents the capacitor from discharging by supplying power to the automobile""s or commercial vehicle""s electrical system when the engine is not running. At the same time, the battery can be used to power accessory devices (e.g., interior lighting or heater within the vehicle) when the engine is not running.
Still further, the method aspects of the present invention include starting the vehicle engine when the vehicle battery is adequately charged while keeping the magnetic switch or FET open. This permits the capacitor to singly supply power to the starter and starter solenoid. Thus, engine starting is faster and more efficient as compared with conventional starting methods. Furthermore, if the battery is discharged to such an extent that the ECU and the starter magnetic switch coil can not be energized, the vehicle operator can close the circuit, preferably using the boost button, as the operator turns the ignition switch to start the vehicle so that the capacitor-supplied power can be provided for all functions of starting directly from the capacitor.